Spin, tangential device for projectiles



Oct. 16, 1962 (.Z. F. LAAGER SPIN, TANGENTIAL DEVICE FOR PROJEC TILES Filed Sept. 23, 1959 A H l 9 25 22 2 Sheets-Sheet l INVEN TOR. CRESTON F LAAGER ATTORNEY$= Oct. 16, 1962 c. F. LAAGER 3,053,423

SPIN, TANGENTIAL DEVICE FOR PROJECTILES Filed Sept. 23, 1959 2 Sheets-Sheet 2 INVENTOR. CRESTON E LAAGER BY 1;. W l a. ml aw ATTORNEY$= United States Patent r 3,058,423 SPIN, TANGENTIAL DEVICE FOR PROJECTILES Creston F. Laager, Beverly, N.J., assignor to the United States of America as represented by the Secretary of the Army Filed Sept. 23, 1959, Ser. No. 841,907 2 Claims. (Cl. 102-51) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a means and method for imparting a high rate of stabilizing spin to a projectile without the necessity for having the usual rifiing in a gun barrel and has for an object to provide such a projectile different desired rates of spin by control of either or both the degree of pressure in a chamber carried by the projectile and the sizes of a plurality of reaction nozzles connected to said chamber and through which said chamber is vented.

Another object is to provide a projectile which begins its spin on leaving the barrel of a gun.

A further object is to provide a projectile capable of a high rate of spin.

Yet another object is to provide a novel round of ammunition capable of utilizing some of the energy of the propellant in a different and less wearing manner than usual to effect spin in a projectile.

The more the twist given to lands and grooves in a gun the greater will be the spin that will be imparted to a projectile with a given charge of propellant, but the greater also will be energy absorption by the gun and the shorter will be its useful life where high rotational speed with high velocity of the projectile are desired. The limitations of the lands and grooves for producing spin have the objection of limiting velocity also.

According to the present invention these objections and limitations have been overcome and a projectile is given a rotational spin of a desired value after leaving a. gun barrel having no rifling. Specifically a gas pressure chamber is provided in a projectile and pressure is supplied thereto preferably from a separate cartridge carried within said chamber and fired in response to the firing of a propelling charge for the projectile. An alternative way of supplying gas pressure to said chamber is to take in hot propellant gas. In either event pressure from said chamber is vented through a plurality of similar, angularly and equally spaced reaction nozzles to generate stabilizing spin.

Referring to the drawings:

FIG. 1 shows a longitudinal sectional view on the line 1-1 of FIG. 2, partly in section, of a preferred embodiment of this invention and with parts cut away to reduce its overall length, the parts cut away being well known and possessing no novelty in this invention;

FIG. 2 is a section on the line 22 of FIG. 1;

FIG. 3 illustrates another embodiment of this invention;

FIG'. 4 exemplifies yet a further modification of this invention.

In FIG. 1 some usual type of cartridge case 10, is filled with a desired type of propellant 11 and crirnped or otherwise secured to a projectile 12 of any type. Unlike the usual projectile the present one is provided therein with a chamber 13 of strength to retain gas under high pressure for the purpose of ejecting such gas through reaction nozzles for the purpose of obtaining spin. In this preferred embodiment a firing pin 14 is moved forward under impetus of gas pressure generated by burning propellant 11 after that pressure has reached a value sufiicient to rupture the shear pin 15. A threaded metal plug 33 reinc tains a firing pin in place as illustrated and contains a passageway 16 through which propellant gas enters to actuate the firing pin 14 engaging a percussion primer 32 in the left or base end of cartridge 17 enclosed in a thin walled aluminum container 18. The desired pressure in chamber 13 is obtained from cartridge 17 and its duration by the burning rate of the explosive in this cartridge. As shown in FIGS. 1 and 2 the reaction ventun' nozzles 19 are shown as being three in number and equidistantly spaced angularly to obtain spin of the projectile. Each nozzle 31 is formed in a block of refractory or heat and wear resistant material such as a threaded metal ceramic or cermet nozzle of suitable character. An adapter 20 is in threaded engagement with the main body of the projectile at 21 and with the pressure chamber 13 at 22. To shield any explosive in the projectile from preignition by a heat, shock or pressure wave from either the propellant 11 or explosive in cartridge 17, a strong steel wall or bridge 23 reinforces the adapter wall 20 in which screwed. The body portion 24 of the projectile may contain any suitable high explosive, detonator, or other appropriate material. The nylon pellets 34 retain the threads against becoming disengaged by their gripping action. 0 rings 25 seal the threaded joints against hot gas leakage. A disc 27 of thermal insulating material may further safeguard any projectile explosive carried in its main body portoin but is usually not needed, the space 26 being an adequate dead air space. A rear bearing surface 28 is of a size to guide the projectile and so also is the front bearing surface 29 during its travel in a gun barrel. The customary nose cone or windshield 30 is provided for the usual purpose.

Preferably the present round is constructed to have ignition of cartridge 17 timed with respect to movement of the projectile in the gun to have a pressure build up in chamber 13 about the time the projectile leaves the gun and not much before that time. However this factor is not critical because the inner walls of the gun bore are so close to the nozzle 19 that little or no useful work can be performed by these nozzles until after the projectile has left the muzzle of the gun. The chamber 13 is spaced from the main body portion 24 of the projectile for purposes of safety against preignition of explosive carried by the projectile, and to provide a reservoir for the high pressure gas. However, the need for having the nozzles adjacent or substantially transversely alined vw'th the center of gravity of the projectile may require the adapter to be less bulky axially and may necessitate the addition of counter-weights carried far in rear of these nozzles. Thus the nozzles 19 may be in a forward portion of chamber 13 and the rear walls of this chamber may be of heavier and more dense metal. Adjustment in rotational velocity of spin is possible by removal of nozzles 19 and the substitution of smaller or larger ones depending on whether duration of spin as well as rate of spin is to be reduced or increased. So also the degree of pressure in chamber 13 may be varied by a change in the composition of the explosive in the cartridge 17.

From the foregoing description, the operation of the present round of ammunition taken in connection with the drawing may be seen to involve a smooth bore gun or at least one in which any lands and grooves become unnecessary. On firing the propellant in any manner the projectile moves forward in the gun. Gas pressure from the propellant actuates the firing pin 14 after rupture of the shear pin causing the cartridge 17 to be fired perhaps during movement of the projectile in the gun. On leaving the muzzle, the nozzles become uncovered causing gas pressure to issue through the nozzles causing spin of the projectile. Uncovering the nozzles is what effects rotation.

The reference numerals applied to FIGS. 1 and 2 have been used in FIG. 3 but with the addition of the letter a where the parts are similar. The cartridge case a contains propellant for firing the projectile 12a from a gun without the necessity for rifling to impart spin to the projectile. A gas pressure chamber 13a is contained in the projectile. Unlike the FIG. 1 round, that in FIG. 3 has the reaction nozzles 19a located in a rear tapered part of chamber 13a to allow propellant gas to enter through nozzles 19a into chamber 13a during movement of the projectile within a gun barrel. Ingress of gas to chamber 13:: ceases on the projectile leaving the gun and egress of gas is then from chamber 13a through the nozzle producing rotation of the projectile. Mention of the remaining parts need not be made in view of the description of FIG. 1.

In the species shown by FIG. 4 propellant gas enters the chamber 13b through the inlet passageway 1611 after rupture of the disc 33, by the propellant gas pressure opens the one way valve 40 mounted on the valve stem 35. A valve stem guide 36 guides opening and closing movements of the valve. Closing movement caused by the projectile emerging from the gun barrel occurs when the pressure inside chamber 13b exceeds the outside air pressure. Spring 37 acts to maintain a normal closed condition and assist valve closure. Here elements described in connection with FIG. 1 have been repeated with the addition of the letter b following the reference numerals. The threaded inlet block 1612 clamps the frangible plate or disc 33 in place. The disc is calculated to rupture at a selected gas pressure. The nozzles 19b are shown in FIG. 4 in a forward portion of the chamber 13b. Gas from the propellant charge raises the valve 40 and is trapped at its maximum value until released by the uncovering of the nozzles.

Among the advantages of this invention may be mentioned an attainment of a high spin in a projectile without the energy consumption and velocity limiting impediment of the customary rifling. Substantial initiation of spin occurs on the projectile leaving the muzzle and in response to the reaction nozzles being opened or uncovered by the projectile emerging from the gun where these nozzles had been largely closed by the gun barrel. The form shown in FIGS. 1 and 2 have the advantage in the simpler and easier control of rotational speed by the size and contents of the cartridge 17. Control of such spin by change in the size and character of the nozzles 19 is not as readily obtainable as is the change in character of the cartridge 17, however such change in nozzles is believed to be simpler than variation in size or composition of the main propellant 11 affecting range and muzzle velocity. Gas entering chamber 13a in FIG. 3 through the nozzles does not produce any substantial tendency for the projectile to spin but the discharge of the same gas through said nozzles does effect such spin in the air in flight.

I claim:

1. In a gun fired, high speed, spin stabilized, ogival projectile having a chamber therein adjacent the rear end portion thereof, reaction nozzles extending from said chamber to the outside of a peripheral wall of said pr0- jectile, means including a gas producing charge for building up pressure in said chamber during forward movement of said projectile within a gun barrel, and means for passing substantially all pressure in said chamber through said nozzles without any portion of said chamber pressure being utilized for forward propulsion of said projectile, said nozzles being located forward of a rear end of said projectile adjacent a longitudinal center of gravity of said projectile, said nozzles extending substantially tangentially to the periphery of said projectile in a plane transverse to the longitudinal axis thereof, said nozzles comprising threaded circular blocks in said projectile in an outer wall containing a venturi passageway in each nozzle block, whereby each of said nozzles may be replaced for a rate of spin adjustment and renewal.

2. A projectile according to claim 1 in which a passageway is provided through a rear wall portion, said first mentioned means including a propellant charge in said chamber, and a valve mechanism is provided for closing said passageway.

References Cited in the file of this patent UNITED STATES PATENTS 36,686 Callender Oct. 14, 1862 1,285,599 Bennett Nov. 26, 1918 2,369,924 Sittig Feb. 20, 1945 2,883,933 King Apr. 28, 1959 2,946,261 Crockett July 26, 1960 

